Yogurt is a product of bacterial fermentation of milk. Here we propose to provide the bacterium Lactobacillus bulgaricus genetic information required in order to produce a certain type of protein called “fluorescent”. The result of the manipulation should be getting a new bacterial strain for the manufacture of yoghurt fluorescent !! :-) Suddenly eating yogurt is much more fun, since it will shine a light in purple :-) !
Isolate bacteria from yogurt
We separate the 2 species of bacteria found in yogurt (j'ai pris un yaourt bulgare), Lactobacillus delbrueckii sp. bulgaricus et Streptococcus thermophilus. Why I spread a dilute solution of yogurt on a Petri dish containing a nutrient medium (by LB, I had it). After 24h of growth at 37 ° C, there are a multitude of circular bacterial colonies. Microbiology is generally accepted that a colony has only one ancestor bacteria as, ie bacteria within a given colony are all the same, we say they are “clones”. Lactobacillus and Streptococcus do not have the same form of cell envelope, Lactobacillus is a bacillus and has a rod-shaped body, Streptococcus cocci and is a spherical body and has a (see pictures). To find it type of bacteria colonies were formed, I take some of this colony and put them on glass slides so they can be easily observed under a microscope.
The fluorescent protein
I will use a low plasmid copy number (order not to destabilize our host beyond measure) gene with the “Green Fluorescent Protein” (GFP). He will speak through a non-regulatable promoter says “constitutive”, to ensure the level of expression of our gene. (I will put the map of plasmid later).